The present invention relates generally to shielding cages used to shield electronic modules from electromagnetic interference, and more particularly to shielding cages that accommodate multiple modules.
In the prior art, electronic circuitry requiring shielding from electromagnetic interference (EMI) is often mounted into a sheet metal chassis, or housing, that suppresses EMI signals. Although prior art EMI-shielded cages provided some EMI suppression, they did not provide a means by which a chassis front panel can be well-grounded. Loose-fitting chassis components provide poor electrical contacts. Depending upon the power level and frequency of EMI, loose-fitting chassis components usually provide poor EMI shielding.
In order to solve this problem, the art has developed metal shielding cages which are attached to circuit boards. In these known cages, a single shielding cage is either constructed from a single sheet of metal or from two sheet metal pieces. In order to provide shielding for electronic components that are used in routers and servers and the like, a single shielding cage must be provided for a single module or device. These modules are spaced apart widthwise on the circuit board and this arrangement takes up a large amount of space. The modules may have a small form-factor pluggable (“SFP”) structure and may include optical transceivers, electrical adapters or the like. In the transceiver configuration, the device receives optic data signals, converts them into electrical signal and transmits the electrical signals onto an electrical interface, typically arranged by way of circuits on a circuit board. Cages are provided which are mounted to a device circuit board and which provide a grounded shield against EMI.
It is therefore desirable to provide a metal shielding cage that accommodates multiple modules or electronic adapters which are securely grounded to ground circuits of a circuit board.